(a) Field of the Invention
The present invention relates to low-pin count fan speed control and more particularly to a low-pin count fan speed control system and a method thereof, wherein fewest pins (4, 5 or 6 pins) are used on a chip to achieve same functions of an existing solution with 8 pins or more.
(b) Description of the Prior Art
In a wave of technologies which are progressed continuously, a computer has already been one of indispensable tools in a life of a contemporary person and a computer has brought to the contemporary person with a lot of conveniences. The computer includes primarily a CPU (Central Processing Unit) to serve as an operating center of the computer, and a processing speed of the computer is required to be faster and faster by the contemporary person. Therefore, in order to comply with usage requirements of the contemporary person, an operating frequency of the CPU is also improved relatively fast. Yet, high temperature which is produced when the CPU is operating needs to be dissipated through a heat dissipation device and most of the heat dissipation devices use fins and air convection resulted from operation of a fan to cool down the CPU.
In terms of an ordinary fan, when a user turns on a computer host, the fan inside the computer host will start slowly until reaching to a fixed rotation speed, so that high temperature produced by the CPU can be dissipated by air convection to effectively avoid instability of the computer system by too high the temperature. Nevertheless, when the computer is used for a long time, external dusts and impurities will be adsorbed due to statics produced by operation of the fan and will be filled into the fan after being accumulated for a long time. As a voltage is smaller when the fan starts, in a beginning, a rotation speed will be affected by the dusts and impurities that the fan will be jammed or cannot operate smoothly, further causing the fan to be damaged or even unable to effectively control the CPU temperature that the computer system is unstable and down.
Moreover, an existing chip sold on a market to control the operation of the fan requires 8 pins or more that complete fan control functions can be provided. However, in spite that this chip of 8 pins or more for controlling the fan is provided with multiple functions, as there are too many pins, a packaging cost for the chip is increased and a production cost is increased as an area of PCB (Printed Circuit Board) is increased.
As a result, there are related vendors who developed a low-pin count (e.g., 5 pins) chip to attempt to reduce the production cost. Although being able to reduce the chip packaging cost, decrease the PCB area and reduce the production cost, this low-pin count chip only controls a positive temperature regulation slope unit of the fan and is not multi-functional as the previous 8-pin chip. Therefore, although the price of the low-pin count chip is cheap, the functions are not robust relatively.